Flat panel display

ABSTRACT

A flat panel display is provided. The flat panel display includes a display panel. A light guide plate is disposed below the display panel. At least one optical film is disposed between the display panel and the light guide plate. At least one illuminating device package is disposed in proximity to the side of the light guide plate. The illuminating device package includes an illuminating semiconductor device and a lens encapsulating the illuminating semiconductor device. The lens includes two reflective surfaces disposed at either side of a central axis. A plurality of diffractive surfaces are disposed between the reflective surfaces. Each of the diffractive surfaces has a tilt angle respective to the central axis. A first portion of light beams incident to each of the reflective surfaces is reflected to at least one diffractive surface and then diffracted and collected into a first convergent angle.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a division of U.S. application Ser. No.11/153,889, filed on Jun. 14, 2005, entitled “Light Emitting DiodePackage,” which claims priority to Taiwanese Patent Application No.93117821, filed Jun. 18, 2004, the contents of both applications areincorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a flat panel display, and moreparticularly, to a flat panel display including a side illuminatinglight emitting diode package having a small degree divergent angle.

2. Description of the Prior Art

In recent years, display technologies have advanced significantly, andafter continuous research and development, products including liquidcrystal displays (LCDs), plasma displays, and organic light emittingdiode displays of various sizes have been widely utilized in variousindustries. Essentially, the direction of development of the displayindustry has been moving toward a direction of high brightness and highyield to manufacture more valuable and cost-effective products for theindustry. Of all critical components of a display, the backlight moduleutilized for providing the light source has been recognized as one ofthe most important parts for determining the effectiveness of theproduct. Hence, a well-designed backlight module is able to effectivelyincrease the brightness of the display and also expand the flexibilityof other components during the fabrication process, whereas a poorlydesigned backlight module will not only provide a limited brightness butalso influence the performance of the display.

Typically, the backlight module is divided into two categories: edgelight and direct-underlying. However, backlight modules utilizing lightemitting diode as the light source have also become increasinglypopular. Essentially, a backlight module combined with light emittingdiodes is able to provide advantages including high luminosity, highdetail, and high coloration, without the use of mercury. Consequently,the backlight module can be applied in numerous fields including cars,displays, televisions, and portable electronic products, and when alight emitting diode is utilized as a light source, the illuminationdirection of the light emitting diode has to be carefully manipulated togenerate an effective light source for increasing the overall brightnessof the display product.

FIG. 1 is a perspective diagram showing a conventional light emittingdiode package 10. As shown in FIG. 1, the light emitting diode package10 includes a packaging substrate 12 and a light emitting diode chip 14.In general, the flow of an electrical current through the PN junction ofthe light emitting diode chip 14 will facilitate electrons to combinewith electron holes to produce light. Since light is projected indifferent directions, most of the light will be collected into a ±60°divergent angle. Nevertheless, when the light emitting diode package 10is applied to the side of a light device, the illumination intensityproduced by the divergent angle 16 will become unsatisfactory.

FIG. 2 is a perspective diagram showing another conventional lightemitting diode package 30. As shown in FIG. 2, the light emitting diodepackage 30 includes a hemispherical lens 32. When light is projectedfrom the light emitting diode package 30, the field of illumination 34produced will travel along the axis 36 of the light emitting diodepackage 30 as a result of the influence of the hemispherical lens 32.Most of the light produced by the light emitting diode package 30 isprojected upward, whereas a small portion of the light is projected awayfrom the two sides of the light emitting diode package 30.

FIG. 3 is a perspective diagram showing the light emitting diode package30 from FIG. 2 disposed on the sideline of a light guide plate 38. Asshown in FIG. 3, the light emitting diode package 30 usually functionstogether with a reflector 42 in order to control the direction of thelight beams for achieving satisfactory illumination. Preferably, thereflector 42 functions to reflect and straighten the light produced bythe hemispherical lens 32 to form a virtually parallel light 44 beforeentering the light guide plate 38 and after a series of opticaltransformations, a uniform and flat light source is produced for thedisplay.

A nearly parallel and uniform light 44 can be produced by combining thelight emitting diode package 30 with the reflector 42. However, thelight has to go through a series of medium conversions and after eachconversion, and a part of the light will be absorbed by the medium inthe form of energy and then transform the energy to heat energy in themedium. As a result, the illumination will be greatly decreased aftergoing through numerous medium conversions.

Therefore, it has become a popular topic for the industries to develop anew light emitting diode package that does not only have a smalldivergent angle, but also qualifies the need for achieving highillumination efficiency without having to go through numerous mediumconversion processes.

It is therefore an objective of the present invention to provide a lightemitting diode package for solving the above-mentioned problems.

BRIEF SUMMARY OF THE INVENTION

An embodiment of a light emitting diode package in accordance with thepresent invention comprises a light emitting diode package and a lensencapsulating the light emitting diode package. The lens furthercomprises two reflective surfaces disposed at either side of a centralaxis, and a plurality of diffractive surfaces disposed between thereflective surfaces and each of the diffractive surfaces having a tiltangle respective to the central axis, in which portions of light beamsincident to each of the reflective surfaces are reflected to at leastone diffractive surface and then diffracted and collected into aconvergent angle.

In contrast to the conventional light emitting diode package, anembodiment of a light emitting diode package in accordance with thepresent invention utilizes a semi vase-shaped lens to package a lightemitting diode chip, in which the lens also includes both reflectivesurfaces and diffractive surfaces. After the light enters the reflectivesurface while the incident angle is greater than the critical angle, atotal internal reflection is generated to inhibit the travelingdirection of the light projected from the light emitting diode, in whichthe light has a great divergent angle. Next, the diffractive phenomenongenerated when light projected to the diffractive surface is utilized todirect the light to a horizontal direction within ±25°, and at the sametime, light also coming from the light emitting diode chip havingsmaller divergent angle is diffracted to a horizontal direction within±25°. Consequently, an embodiment of a light emitting diode package inaccordance with the present invention can be utilized as an excellentside illuminating light source for increasing the effectiveness of theillumination, in which the light projected from the light emitting diodechip can be guided only through the lens and air to the light guideplate, thereby by eliminating the need of going through any other mediumconversions.

An embodiment of a light emitting diode package in accordance with thepresent invention, comprises, a light emitting diode device and a lensencapsulating the light emitting diode device. The lens furthercomprises two reflective surfaces disposed at either side of a centralaxis, and a plurality of diffractive surfaces disposed between thereflective surfaces, each of the diffractive surfaces having a tiltangle respective to the central axis, wherein portions of light beamsincident to each of the reflective surfaces are reflected to at leastone diffractive surface and then diffracted and collected into aconvergent angle.

An embodiment of a backlight module in accordance with the presentinvention, comprises, a light guide plate, at least one optical filmdisposed above the light guide plate, and at least one illuminatingdevice disposed in proximity to the side of the light guide plate. Theilluminating device further comprises an illuminating semiconductordevice and a lens disposed above the illuminating semiconductor device.The lens further comprises at least one reflective surface and at leastone diffractive surface disposed in proximity to the reflective surfaceand the diffractive surface having a tilt angle respective to thecentral axis of the lens. A first portion of light beams is reflected bythe reflective surface to the diffractive surface, diffracted by thediffractive surface, and collected into a convergent angle after thelight produced by the illuminating semiconductor device enters the lens.

An embodiment of a flat panel display in accordance with the presentinvention, comprises, a display panel, a light guide plate disposedbelow the display panel, at least one optical film disposed between thedisplay panel and the light guide plate, and at least one illuminatingdevice disposed in proximity to the side of the light guide plate. Theilluminating device further comprises an illuminating semiconductordevice, and a lens disposed above the illuminating semiconductor device.The lens further comprises at least one reflective surface, and at leastone diffractive surface disposed in proximity to the reflective surfaceand the diffractive surface having a tilt angle respective to thecentral axis of the lens. A first portion of light beams is reflected bythe reflective surface to the diffractive surface, diffracted by thediffractive surface, and collected into a convergent angle after thelight produced by the illuminating semiconductor device enters the lens.

A method for forming a flat panel display includes disposing a lightguide plate below a display panel. At least one optical film is disposedbetween the display panel and the light guide plate. At least oneilluminating device package is disposed in proximity to the side of thelight guide plate. A method for forming the illuminating device packagecomprises forming a light emitting diode device over a substrate. A lensis formed to encapsulate the light emitting diode device. The lensincludes two reflective surfaces disposed substantially symmetrically ateither side of a central axis. The reflective surfaces are configured toreflect portions of light beams to at least one of the diffractivesurfaces. A plurality of diffractive surfaces separate the reflectivesurfaces. The diffractive surfaces are configured to diffract thereflected light beams into a convergent angle. Each of the diffractivesurfaces has a tilt angle respective to the central axis.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention.

FIG. 1 is a perspective diagram showing a conventional light emittingdiode package.

FIG. 2 is a perspective diagram showing another conventional lightemitting diode package.

FIG. 3 is a perspective diagram showing the light emitting diode packagefrom FIG. 2 disposed on the sideline of a light guide plate.

FIG. 4 and is a perspective diagram showing the cross-section of thelight emitting diode package according to a first embodiment of thepresent invention.

FIG. 5 is a perspective diagram showing the convergent angle of thelight emitting diode package of FIG. 4.

FIG. 6 is a perspective diagram showing the cross-section of the lightemitting diode package according to a second embodiment of the presentinvention.

FIG. 7 is a perspective diagram showing the external view of the lightemitting diode package from FIG. 6.

FIG. 8 is a perspective diagram showing combination of the lightemitting diode package with another backlight module according to oneembodiment of the present invention.

FIG. 9 is a perspective diagram showing combination of the lightemitting diode package with another backlight module according toanother embodiment of the present invention.

FIG. 10 is a perspective diagram showing combination of the lightemitting diode package with another backlight module according to stillanother embodiment of the present invention.

FIG. 11 is a perspective diagram showing application of the lightemitting diode package to a flat panel display according to yet anotherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 4 and is a perspective diagram showing the cross-section of thelight emitting diode package 100 according to the first embodiment ofthe present invention, and FIG. 5 is a perspective diagram showing theconvergent angle of the light emitting diode package 100 of FIG. 4. Asshown in FIG. 4, the light emitting diode package 100 includes a lightemitting diode chip 102, a packaging substrate 104 utilized forsupporting the light emitting chip 102, a lens 106 for encapsulating thelight emitting diode chip 102, and a circuit board 108. Fabricated byinjection molding, the lens 106 is comprised of a polycarbonate (PC)lens, a polymethylmethacrylate (PMMA) lens, a resin lens, or a glasslens. Additionally, the lens 106 includes two reflective surfaces 112disposed on two sides of a central axis 114 of the lens 106, in whicheach reflective surface 112 is disposed symmetrically to the centralaxis 114 and each reflective surface 112 includes a curved surface. Thelens 106 also includes a plurality of diffractive surfaces 116 disposedbetween each of the reflective surfaces 112, in which a tilt angle(indicated by θ₁, θ₂, θ₃, and θ₄ in the figure) is formed between eachdiffractive surface 116 and the central axis 114.

In general, the flow of an electrical current from a circuit board 108through the light emitting diode 102 to the PN junction will facilitatethe electrons to combine with electron holes to produce light 118 and122. Since the light 118 and 122 is projected to different directions, aportion of the light 118 (with a divergent angle greater than 40-50° ofthe light) is projected to the two reflective surfaces 112. Since thelens 106 is a denser medium than air, the diffractive coefficient N₁ ofthe lens 106 should be greater than the diffractive coefficient N₂ ofair. Consequently, when the light 118 projects to the incident angle αof the reflective surface 112 matches a condition of “sin α≧N₂/N₁”, thenthe light 118 will generate a total internal reflection on the tworeflective surfaces 112 separately and reflect to at least onediffractive surface 116.

After the light 118 reaches each diffractive surface 116, an incidentangle χ will be generated and at the same time, a diffractive phenomenonwill also result on the diffractive surface 116 and the surface of theair. In other words, the light 118 will enter the diffractive surface116 at the incident angle χ, its traveling path will deviate from thenormal of the diffractive surface 116, and the light 118 will exit thediffractive surface 116 at a diffractive angle χ′.

The relationship between the incident angle χ and the diffractive angleχ′ is as follows:

N ₁ /N ₂=sin χ′/sin χ

Since the diffractive coefficient N₁ is greater than the diffractivecoefficient N₂, the diffractive angle χ′ will also be greater than theincident angle χ. Therefore, after a series of total internal reflectionand diffraction phenomenon, the diverged light 118 will be collectedinto a convergent angle θ and the convergent angle will form a ±25°angle respective to the central axis 114. (Please refer to FIG. 5)

On the other hand, since the light 122 projected from the light emittingdiode chip 102 includes a smaller divergent angle, the light 122 will bedirectly projected into at least a diffractive surface 116 therebygenerating a diffractive phenomenon, as shown in FIG. 4. In other words,the light 122 will enter the diffractive surface 116 at the incidentangle γ, its traveling path will deviate from the normal of thediffractive surface 116, and the light will exit the diffractive surface116 as a diffractive angle γ′.

The relationship between the incident angle γ and the diffractive angleγ is as follows:

N ₁ /N ₂=sin γ′/sin γ

Since the diffractive coefficient N₁ is greater than the diffractivecoefficient N₂, the diffractive angle γ′ will also be greater than theincident angle γ. Eventually, the light 122 will be collected into theconvergent angle θ. (Please refer to FIG. 5)

According to the lens 106 of the present invention, a total internalreflection phenomenon generated by utilizing the light 118 to enter thereflective surface 112, in which the incident angle α is greater thanthe critical angle, is utilized to inhibit the traveling direction ofthe light 118 projected from the light emitting diode chip 102, in whichthe light 118 includes a great divergent angle. Next, the light 118 isentered into the diffractive surface 116 to generate a diffractivephenomenon for re-directing the light 118 to a horizontal directionwithin ±25°. At the same time, the light 122 with the smaller divergentangle, which has also been projected from the light emitting diode chip102, is diffracted directly to the horizontal direction within ±25°.Consequently, the light emitting diode package 100 becomes a packagethat is able to “project light from the sides” and by combining thelight source with the module structure, the light 118 and 122 projectedfrom the light emitting diode 102 can be directed to a light guide plateby just going through the lens 106 and air and without having to gothrough any other medium conversions, thereby greatly improving theillumination efficiency and reducing the need of utilizing auxiliarydevices.

According to the mechanisms described previously, the light emittingdiode package 100 of the present invention includes the following keycharacteristics: First, the design of each reflective surface 112 has toallow the light 118 with the bigger divergent angle emitted from thelight emitting diode chip 102 to generate a total internal reflection,and secondly, the design of each diffractive surface 116 has to allowthe light 118 and 122 to generate an appropriate amount of deviationduring diffraction, thereby successfully collecting the light into theconvergent angle θ. As shown in FIG. 4, since each reflective surface112 is represented by a curving surface, the first characteristic can beachieved by controlling the curvature of each reflective surface 112 andthe material of the lens 106 (meaning to control the diffractivecoefficient of the lens), whereas the second characteristic can beachieved by controlling the tilt angle between the each diffractivesurface 116 and the central axis 114 and the material of the lens 106.As shown in FIG. 4, an example is provided by forming an acute angle βwith two diffractive surfaces 116 and each reflective surface 112, and atriangular surface is formed by the rest of the diffractive surfaces116.

Alternatively, a total internal reflection can be achieved by applying asuitable reflective material over the surface and each diffractivesurface can also be manipulated by other methods. Please refer to FIG.6. FIG. 6 is a perspective diagram showing the cross-section of thelight emitting diode package 200 according to the second embodiment ofthe present invention. As shown in FIG. 6, each of the two diffractivesurfaces 216 forms an acute angle β with each reflective surface 212separately whereas the rest of the diffractive surfaces form ahemispherical surface 218. Please refer to FIG. 7. FIG. 7 is aperspective diagram showing the external view of the light emittingdiode package 200 from FIG. 6. As shown in FIG. 7, the light emittingdiode package 200 is in fact a semi-vase-shaped structure, in which thestructure includes a circuit board 208, a lens 206, a light emittingdiode chip and a packaging substrate for supporting the light emittingdiode chip, similar to the ones shown in FIG. 4.

Additionally, each reflective surface does not have to be disposedsymmetrically on the two sides of the central axis, but can also haveother variations, and the two diffractive surfaces connected to eachreflective surface may also form different acute angles with otherreflective surfaces. Essentially, variations related to the twocharacteristics described are all included within the present invention.

FIG. 8 is a perspective diagram showing combination of the lightemitting diode package 100 with a backlight module 230. As shown in FIG.8, the light emitting diode package 100 is disposed on the side of alight guide plate 232 of the backlight module 230 and due to the smalldivergent angle (±25°), almost all the light 234 is directed into thelight guide plate 232 after the light 234 is projected from the lightemitting diode package 100. Next, the light 234 is reflected upward viathe diffusion point 236 located on the bottom of the light guide plate232 and then directed to a display through an optical mechanism 238composed of controlling sheets and thin film materials, in which theoptical mechanism 238 can be a diffusion plate or a prism.

FIG. 9 is a perspective diagram showing combination of the lightemitting diode package 100 with a backlight module 250. As shown in FIG.9, the light emitting diode package 100 is disposed on the side of alight guide plate 252 of the backlight module 250, in which the lightguide plate 252 is a wedge shaped light guide plate. Similarly, due tothe small divergent angle (±25°), almost all the light 254 is directedinto the light guide plate 252 after the light 254 is projected from thelight emitting diode package 100. Next, the light 254 is reflectedupward via the structure of the light guide plate 252 and the diffusionpoint 256 located on the bottom of the light guide plate 252 and thendirected to a display through an optical mechanism 258 composed ofcontrolling sheets and thin film materials, in which the opticalmechanism 258 can be a diffusion plate or a prism.

FIG. 10 is a perspective diagram showing combination of the lightemitting diode package 100 with a backlight module 270, and in order toclearly demonstrate the relationship between each component, FIG. 10 isshown from a 3-D perspective. As shown in FIG. 10, a plurality of lightemitting diode packages 100 are disposed on two sides of a light guideplate 272, in which the light guide plate 272 is a double wedge-shapedlight guide plate. Similarly, due to the small divergent angle (±25°),almost all the light 274 is directed into the light guide plate 272after the light 274 is projected from the light emitting diode packages100. Next, the light 274 is reflected upward via the diffusion point 276located on the bottom of the light guide plate 272 and then directed toa display through an optical mechanism 278 composed of controllingsheets and thin film materials.

FIG. 11 is a perspective diagram showing application of the lightemitting diode package 100 to a flat panel display 300. As shown in FIG.11, the flat panel display 300 includes display panel 302 and abacklight module 330, in which the backlight module 330 is disposedbelow the display panel 302. The backlight module 330 also includes alight guide plate 332 therein and the light emitting diode package 100of the present invention is disposed on the side of the light guideplate 332. Similar to the previous embodiments, due to the smalldivergent angle (±25°), almost all the light 334 is directed into thelight guide plate 332 after the light 334 is projected from the lightemitting diode package 100. Next, the light 334 is reflected upward viathe diffusion point 336 located on the bottom of the light guide plate332 and then directed to the display panel 302 through an opticalmechanism 338 composed of controlling sheets and thin film materials, inwhich the optical mechanism 338 can be a diffusion plate or a prism.

By utilizing a semi-vase-shaped lens to package a light emitting diodechip, in which the lens also includes both reflective surface anddiffractive surface, the light entering the reflective surface is ableto generate a total internal reflection phenomenon for inhibiting thetraveling direction of the light having a great divergent angle, whichhas been projected from the light emitting diode chip, and thediffractive surface is able to direct the light to a horizontaldirection within ±25°. Essentially, the light emitting diode package ofthe present invention is not only able to provide an excellent sideillumination characteristic, but also able to eliminate the process ofgoing through numerous medium conversions to direct light to the lightguide plate. As a result, the light emitting diode package of thepresent invention can be utilized as a side-illuminating light sourcedevice for fabricating display products with much lower costs, simplerstructures, and better yield.

In contrast to the conventional light emitting diode package, the lightemitting diode package of the present invention utilizes asemi-vase-shaped lens to package a light emitting diode chip, in whichthe lens also includes both reflective surfaces and diffractivesurfaces. After the light enters the reflective surface while theincident angle is greater than the critical angle, a total internalreflection is generated to inhibit the traveling direction of the lightprojected from the light emitting diode, in which the light has a greatdivergent angle. Next, the diffractive phenomenon generated when lightis projected to the diffractive surface is utilized to direct the lightto a horizontal direction within ±25°, and at the same time, light alsocoming from the light emitting diode chip having smaller divergent angleis diffracted directly to a horizontal direction within ±25°.Consequently, the light emitting diode package of the present inventioncan be utilized as an excellent side illuminating light source forincreasing the effectiveness of the illumination, in which the lightprojected from the light emitting diode chip can be guided only throughthe lens and air to the light guide plate, thereby by eliminating theneed of going through any other medium conversion processes.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention. Accordingly, the abovedisclosure should be construed as limited only by the metes and boundsof the appended claims.

1. A flat panel display comprising: a display panel; a light guide platedisposed below the display panel; at least one optical film disposedbetween the display panel and the light guide plate; and at least oneilluminating device package disposed in proximity to the side of thelight guide plate, wherein each illuminating device package includes: anilluminating semiconductor device, and a lens encapsulating theilluminating semiconductor device, wherein the lens comprises, tworeflective surfaces disposed at either side of a central axis, and aplurality of diffractive surfaces disposed between the reflectivesurfaces, each of the diffractive surfaces having a tilt anglerespective to the central axis, wherein a first portion of light beamsincident to each of the reflective surfaces is reflected to at least onediffractive surface and then diffracted and collected into a firstconvergent angle.
 2. The flat panel display of claim 1, wherein a secondportion of the light beams is projected directly to the at least onediffractive surface, diffracted by the at least one diffractive surface,and collected into a second convergent angle after the light produced bythe illuminating semiconductor device enters the lens.
 3. The flat paneldisplay of claim 1, wherein the lens comprises a polycarbonate (PC)lens, a polymethylmethacrylate (PMMA) lens, a resin lens, or a glasslens.
 4. The flat panel display of claim 1, wherein the at least oneoptical film is a diffuser plate.
 5. The flat panel display of claim 1,wherein the at least one optical film is a prism.
 6. The flat paneldisplay of claim 1, wherein the reflective surfaces are disposedsymmetrically on both sides of the central axis.
 7. The flat paneldisplay of claim 1, wherein the first portion of the light beamsincident to each of the reflective surfaces is reflected to the at leastone diffractive surface after each reflective surface generates a totalinternal reflection.
 8. The flat panel display of claim 1, wherein atleast two diffractive surfaces are disposed symmetrically on both sidesof the central axis.
 9. The flat panel display of claim 1, wherein twoof the diffractive surfaces form an acute angle respective to eachreflective surface and the remaining diffractive surfaces form ahemispherical surface.
 10. The flat panel display of claim 1, whereintwo of the diffractive surfaces form an acute angle respective to eachreflective surface and the remaining diffractive surfaces form atriangular surface.
 11. The flat panel display of claim 1, wherein thelight beams from the illuminating semiconductor device directlyprojected to the at least one diffractive surface is diffracted by theat least one diffractive surface and collected to the first convergentangle.
 12. The flat panel display of claim 1, wherein the at least onediffractive surface is configured to diffract the reflected light beamssuch that the diffracted light beams are substantially parallel to thecentral axis.
 13. The flat panel display of claim 1, wherein the firstconvergent angle with respect to the central axis is between about +25degrees and about −25 degrees.
 14. The flat panel display of claim 1,wherein the reflective surfaces disposed at either side of the centralaxis are separated.
 15. The flat panel display of claim 1, wherein afirst diffractive surface contacts a first reflective surface to form afirst acute angle, a second diffractive surface contacts a secondreflective surface to form a second acute angle, and at least one thirddiffractive surface extends from the first diffractive surface to thesecond diffractive surface to form a hemispherical surface.
 16. The flatpanel display of claim 1, wherein a first diffractive surface contacts afirst reflective surface to form a first acute angle, a seconddiffractive surface contacts a second reflective surface to form asecond acute angle, and at least third one diffractive surface extendsfrom the first diffractive surface to the second diffractive surface toform a triangular surface.
 17. The flat panel display of claim 1,wherein a first diffractive surface contacts a first reflective surfaceto form a first acute angle, a second diffractive surface contacts asecond reflective surface to form a second acute angle, and at least onethird diffractive surface extends from the first diffractive surface tothe second diffractive surface to form a semi-vase-shaped surface. 18.The flat panel display of claim 1, wherein a first diffractive surfacecontacts a first reflective surface to form a first acute angle, asecond diffractive surface contacts a second reflective surface to forma second acute angle, a third diffractive surface contacts the firstdiffractive surface to form a third acute angle, and a fourthdiffractive surface contacts the second diffractive surface to form afourth acute angle.
 19. A method for forming a flat panel display,comprising: disposing a light guide plate below a display panel;disposing at least one optical film between the display panel and thelight guide plate; and disposing at least one illuminating devicepackage in proximity to the side of the light guide plate, wherein amethod for forming the illuminating device package includes: forming alight emitting diode device over a substrate; and forming a lensencapsulating the light emitting diode device, the lens comprising: tworeflective surfaces disposed substantially symmetrically at either sideof a central axis, the reflective surfaces being configured to reflectportions of light beams to at least one of the diffractive surfaces; anda plurality of diffractive surfaces separating the reflective surfaces,the diffractive surfaces being configured to diffract the reflectedlight beams into a convergent angle, each of the diffractive surfaceshaving a tilt angle respective to the central axis.
 20. The method ofclaim 19, wherein forming the lens comprises: forming a firstdiffractive surface contacting a first reflective surface to form afirst acute angle, forming a second diffractive surface contacting asecond reflective surface to form a second acute angle; and forming atleast third diffractive surface extends from the first diffractivesurface to the second diffractive surface to form a hemisphericalsurface, a triangular surface or a semi-vase-shaped surface.